The Holzmaar is the best reserached maar worldwide. It is about 40.000 to 70.000 years old and now about 20 m deep. Starting in the 1980s, the University of Trier, and later on German Research Center for Geosciences in Potsdam until today, numerous drilling cores were taken form the Holzmaar and analysed. New research methods have been testet and optimised here.

During the 16th century tha lake was dammed toward the south to supply Gillenfeld saw mill in the forest about 2 km to the south.


Dürres Maar is about 4.000 years old and has a bock thickness of noy 12 meters. Former is was 9 meters deep. The dürres maar area was made a nature conservancy in 1979 along with the Holzmaar. It represents the second oldest volcanic eruption site in the Holzmaar group and is now filled with a transitional moor.

Hetsche Maar is the oldest maar in the Eifel and it is only 5 meters deep. It is about 200 meters north west of the Dürren Maar and it is depply embedded in the surrounding fields, but visible form the street between Brockscheid and Gillenfeld. It is the smallest maar in the Eifel and created by one to two eruptions. By the way, Hetsche is the Gillenfeld colloquialism for the common toad, a reference to a local inhabitant.